refactor: fix all P0/P1/P2 bugs and architecture issues

Bug fixes (from bugs/ directory):

- Fix cross-module DB queries in 9 modules (homework, grades, parent, diagnostic, elective, proctoring, notifications, scheduling, classes) by routing through data-access functions

- Fix shared/lib <-> auth circular dependency via new session.ts module

- Fix divide-by-zero guard in grades data-access

- Fix audit export data truncation (paginated fetch for full datasets)

- Fix missing transactions in homework grading and elective lottery

- Fix missing revalidatePath in course-plans actions

- Fix frontend permission checks using requirePermission instead of requireAuth

- Fix dashboard role routing using session.user.roles

- Fix student auth pattern (migrate getDemoStudentUser to users module)

- Fix ActionState return type handling in components

Code quality fixes:

- Remove 60+ as type assertions (replace with type guards)

- Remove non-null assertions (use optional chaining or explicit checks)

- Convert dynamic imports to static imports (grades, diagnostic)

- Add React.cache() wrapping for read functions

- Parallelize independent queries with Promise.all

- Add explicit return types to 30+ arrow functions

- Replace any with unknown + type guards

- Fix import type for type-only imports

- Add Zod validation schemas for classes and diagnostic modules

- Extract duplicate code (normalizeRoleName, normalizeBcryptHash, logger IP extraction)

- Add console.error to silent catch blocks

- Fix permission naming consistency (exam:proctor_read -> exam:proctor:read)

Architecture doc sync:

- Update 004_architecture_impact_map.md and 005_architecture_data.json

- Update management-modules-audit.md for P0-7 cross-module fix

Moved deleted proctoring event route to deletes/ folder.

src/modules/textbooks/actions.ts

@@ -3,10 +3,10 @@
 import { requirePermission, PermissionDeniedError } from "@/shared/lib/auth-guard";
 import { Permissions } from "@/shared/types/permissions";
 import { revalidatePath } from "next/cache";
-import { 
-    createTextbook, 
-    createChapter, 
-    updateChapterContent, 
+import {
+    createTextbook,
+    createChapter,
+    updateChapterContent,
     deleteChapter,
     createKnowledgePoint,
     deleteKnowledgePoint,
@@ -15,7 +15,12 @@ import {
     deleteTextbook,
     reorderChapters
 } from "./data-access";
-import { CreateTextbookInput, UpdateTextbookInput } from "./types";
+import type { CreateTextbookInput, UpdateTextbookInput } from "./types";
+
+const getStringValue = (formData: FormData, key: string): string => {
+  const value = formData.get(key)
+  return typeof value === "string" ? value : ""
+}
 
 // ... existing code ...
 
@@ -52,10 +57,10 @@ export async function createTextbookAction(
 ): Promise<ActionState> {
   // ... implementation same as before
   const rawData: CreateTextbookInput = {
-    title: formData.get("title") as string,
-    subject: formData.get("subject") as string,
-    grade: formData.get("grade") as string,
-    publisher: formData.get("publisher") as string,
+    title: getStringValue(formData, "title"),
+    subject: getStringValue(formData, "subject"),
+    grade: getStringValue(formData, "grade"),
+    publisher: getStringValue(formData, "publisher"),
   };
 
   if (!rawData.title || !rawData.subject || !rawData.grade) {
@@ -91,10 +96,10 @@ export async function updateTextbookAction(
 ): Promise<ActionState> {
   const rawData: UpdateTextbookInput = {
     id: textbookId,
-    title: formData.get("title") as string,
-    subject: formData.get("subject") as string,
-    grade: formData.get("grade") as string,
-    publisher: formData.get("publisher") as string,
+    title: getStringValue(formData, "title"),
+    subject: getStringValue(formData, "subject"),
+    grade: getStringValue(formData, "grade"),
+    publisher: getStringValue(formData, "publisher"),
   };
 
   if (!rawData.title || !rawData.subject || !rawData.grade) {
@@ -151,7 +156,7 @@ export async function createChapterAction(
     prevState: ActionState | null, 
     formData: FormData
 ): Promise<ActionState> {
-    const title = formData.get("title") as string;
+    const title = getStringValue(formData, "title");
     
     if (!title) return { success: false, message: "Title is required" };
 
@@ -214,9 +219,9 @@ export async function createKnowledgePointAction(
     prevState: ActionState | null,
     formData: FormData
 ): Promise<ActionState> {
-    const name = formData.get("name") as string;
-    const description = formData.get("description") as string;
-    const anchorText = formData.get("anchorText") as string;
+    const name = getStringValue(formData, "name");
+    const description = getStringValue(formData, "description");
+    const anchorText = getStringValue(formData, "anchorText");
 
     if (!name) return { success: false, message: "Name is required" };
 
@@ -256,9 +261,9 @@ export async function updateKnowledgePointAction(
     prevState: ActionState | null,
     formData: FormData
 ): Promise<ActionState> {
-    const name = formData.get("name") as string;
-    const description = formData.get("description") as string;
-    const anchorText = formData.get("anchorText") as string;
+    const name = getStringValue(formData, "name");
+    const description = getStringValue(formData, "description");
+    const anchorText = getStringValue(formData, "anchorText");
 
     if (!name) return { success: false, message: "Name is required" };